The Maryland Department of Health and Mental Hygiene said Roos' cheese products have presumptively come up positive for Listeria bacteria, although they're still testing them for complete confirmation.

Roos Foods, which is based out of Kenton, Del., includes the following brands: Santa Rosa de Lima, Amigo, Mexicana, Suyapa, La Chapina and La Purisima Crema Nica.

Listeria bacteria can cause listeriosis, a serious infection that usually occurs within three days to 10 weeks of consumption of tainted products. Symptoms include fever, muscle aches, headache, a stiff neck, confusion, loss of balance and convulsions that can be preceded by nausea or diarrhea.

Officials said it's especially important that pregnant women, newborns and the elderly stay clear of tainted products.

Anyone who has symptoms of listeriosis or has consumed a Roos product should contact their health care provider immediately.